JP4497600B2 - Control method for constant power output DC power supply - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a switching power supply apparatus, and more particularly to a DC power supply apparatus that supplies a constant power output and its output power control.
[0002]
[Prior art]
Conventionally, a switching power supply having a circuit configuration as shown in FIG. 3 is used for a power supply apparatus such as a film forming apparatus. In FIG. 3, 1 is a switching converter, D0 is a rectifier diode, C1
Is a smoothing capacitor, Q1 to Q4 are power transistors and form a full bridge with 4
D1 and D2 are diodes connected in the reverse conduction direction with respect to the transistors Q3 and Q4, respectively.
Reference numeral 2 denotes an output transformer of the conversion unit, 3 denotes a rectifier diode of the transformer output, and 4 and 5 denote a smoothing filter reactor and a capacitor, respectively.
[0003]
In order to control the film forming apparatus, constant power control is necessary. Therefore, the output characteristics of the power supply apparatus are as shown in FIG. In FIG. 5, Vo is the output voltage of the power supply device, and Io is the output current.
V1 and I2 are the maximum output voltage and the maximum output current, respectively. V2 and I1 are the output voltage and output current located at both ends of the constant power characteristic, respectively. Therefore, the constant power range is between A and B.
In FIG. 5, for example, if V1 = 500 V and I2 = 40 A, the output capacity of the power supply device is 20 kW (V1 × I1). If I1 × V1 (= I2 × V2), I1 = 20A, and V2 = 250V, 10KW is obtained.
[0004]
Therefore, the output transformer has a capacity of 20 KW and is only used at 10 KW, and the utilization rate is poor. On the other hand, in the switching section composed of the transistors Q1 to Q4, etc., the power transistors Q1 to Q4 are configured as a full bridge, and a well-known pulse width control (PWM) is performed at a constant period T (FIG. 4). . In FIG. 4, the waveforms (a) to (d) indicate that Q1 to Q4 are in the ON state, and the output of the full bridge (primary input of the transformer) has the pulse width t indicated by the waveform (e). Pulse output. When the power supply device output current reaches the maximum value due to constant power output, the output voltage becomes low, and therefore the pulse width t also becomes small. When this voltage is rectified (waveform (f)) and smoothed, The smoothing filter becomes larger.
As described above, the conventional control method has disadvantages such as a low utilization factor of the transformer and a large filter.
[0005]
【task to solve】
The present invention is intended to improve the above-mentioned drawbacks, increase the utilization factor of the transformer, reduce the factor of the output voltage ripple, reduce the size of the transformer and smoothing filter, and further provide a power supply device. The power supply apparatus and its control system that can be miniaturized are provided.
[0006]
[Solution]
In order to solve the above-mentioned problems, the invention of claim 1 provides two constant power output DC power supply units each having a switching converter that outputs a pulse width control waveform, an output transformer, and a rectifying and smoothing unit that rectifies the output of the output transformer. A switch element is connected between the output negative terminal of one of the power supply devices and the output positive terminal of the other power supply device, and one is connected between the output positive terminals and the output negative terminals of the power supply devices. A diode is connected in a polarity with the output terminal side of the power supply device as a cathode, and DC constant power is fed between the output positive terminal of the one power supply device and the output negative terminal of the other power supply device through a smoothing filter. With this configuration, each circuit component, particularly the transformer, can use 100% of its own capacity, and the transformer can be downsized due to its high utilization rate. Output wave Also it can be miniaturized output filter since little of variation. Further, in the configuration of the power supply device, the power supply device can be downsized by downsizing these components having a relatively large size to weight ratio.
[0007]
In order to solve the above-mentioned problems, the invention according to claim 2 is the power supply device according to claim 1, wherein the switching converters are operated synchronously, the output pulse width is 180 ° conduction width, and each output At the beginning of the cycle, the switch elements are turned on to connect the outputs of the respective power supply devices in series to supply power. After a predetermined time of each output cycle, the switch elements are turned off to turn off the outputs of the respective power supply devices. It is a control method characterized by supplying power by connecting in parallel. By this control, the transformer is always 180 ° output state, so that its own capacity can be used 100%, and the output of each output Switch element at the beginning of the cycle,
By turning it ON, it is possible to prevent instability of control due to the recovery current of the diodes 11 and 12 from the series connection to the parallel connection or from the parallel connection to the series connection.
[0008]
Embodiment
FIG. 1 is a circuit showing an embodiment of the present invention, wherein 1-1 and 1-2 are switching converters having the same configuration as the conventional switching converter 1, 6 is an output transformer of the switching converter 1-1, 7 Is an output rectifier of the switching converter 1-2, 9 is a rectifier diode of the output of the transformer 8, 10 is a negative side of the output of the rectifier diode 7, and a positive side of the output of the rectifier diode 9 A high-speed switch (for example, a power transistor), 11 and 12 are diodes connected so that the outputs of two conversion circuits can be operated in parallel through these, and 13 is a two-winding coil wound around the same iron core. Each of the windings is inserted into each of the positive and negative lines operated in parallel by a reactor having a smoothing filter together with the capacitor 14.
[0009]
FIG. 2 shows operation waveforms of the circuit of FIG. In FIG. 1, the conversion circuits 1-1 and 1-2 are operated at the same timing and at the maximum control angle (approximately 180 °). Therefore, the waveforms rectified by the rectifier diodes on the output side are exactly the same (FIGS. 2A and 2B). When the switch 10 is not operating, the two outputs are in parallel operation via the diodes 12 and 13, and when the switch 10 is operating and turned on, the two outputs are connected in series via the switch 10. As a result, the output voltage Vo as the power supply device is twice the output voltage of one circuit.
[0010]
The following control is performed using these operation states. As shown in FIG. 2 (c), when the switch 10 is turned on at the beginning of each output cycle, the output voltage V1 of the rectifier diode 7 is turned on.
And the output voltage V2 of the rectifier diode 9 (where V1 = V2) are connected in series, and the combined output voltage is V1 + V2. After time ts, switch 10 is turned off at time t1. From that point on, the two circuits are in parallel and the combined output voltage is V1 (= V2), and in that state continues until the end of the output cycle t2 (tp period). A period tr from t2 to the beginning t'0 of the next cycle is an operation time for stably performing the switching operation in the switching converters 1-1 and 1-2, and is an extremely short time. t1 is a controllable time and is controlled so as to be a necessary total output voltage V0 (average value).
[0011]
Therefore, the combined output voltage becomes maximum when t1 becomes equal to t2, and becomes V0 max = 2V1 (= 2V2), and becomes minimum when t1 becomes t0, and V0min =
V1 (= V2). Accordingly, the output voltage V0 can be controlled from V1 to 2V1. As shown in Fig. 2 (d), the voltage waveform at the input of the output smoothing filter is based on half of the voltage peak value over the entire output cycle, and the control part that causes output ripple is the wave. Since it is 1/2 of the high value, as can be seen from the waveform (f) in FIG. 4, the waveform has essentially a small ripple component, and therefore the output smoothing filter may be small.
[0012]
As for the current, constant power control as shown in FIG. 5 is performed. Therefore, when the maximum current flows, the output voltage is minimum, and therefore, the two circuits are in parallel throughout the entire output cycle. (In fact, when the output voltage increases, the maximum required current capacity is increased by about 20% because of the series period when the output voltage increases.) As described above, the transformer is always in an almost 180 ° output state, and since the maximum current is allowed to flow in this state, 100% of its own capacity can be used.
[0013]
【The invention's effect】
As described above, in the converter circuit of the DC power supply device having the constant power output characteristic, the output power control is performed by the series / parallel operation of the two converter circuit outputs so that each of the two circuits is always 180 °. Because of the period of output operation, each circuit component, especially the transformer, can use its own capacity 100%, the transformer can be downsized due to its high utilization rate, and the change in the output waveform Since there are few, an output filter can also be reduced in size. In the configuration of the power supply device, the power supply device can be reduced in size by reducing the size of these parts having a relatively large size to weight ratio.
[Brief description of the drawings]
1 is a circuit diagram of an embodiment of the present invention. FIG. 2 is an operation waveform diagram of an embodiment of the present invention. FIG. 3 is a conventional circuit diagram. FIG. 4 is an operation waveform diagram of a conventional circuit. Output characteristics [Explanation of symbols]
1-1, 1-2: Switching converters 6, 8: Output transformers 7, 9: Rectifier diode 10: Switch elements 11, 12: Diode 13: Reactor 14: Capacitor

Claims (1)

   Two constant power output DC power supply devices each having a switching converter that outputs a pulse width control waveform, an output transformer, and a rectifying and smoothing unit that rectifies the output of the output transformer, and an output negative terminal of one of the power supply devices The switching element is connected between the positive output terminals of the other power supply apparatus, and the polarity between the output positive terminals of the power supply apparatus and the negative output terminal is the cathode of the output terminal side of the one power supply apparatus. A diode is connected to the output positive terminal of one power supply device and the output negative terminal of the other power supply device, and two windings wound on the same iron core are connected to each positive and negative line operated in parallel. A smoothing filter having a reactor configured to be inserted and a capacitor connected between the outputs of these reactors is provided, and the switching converters are operated synchronously and the output pulse widths are respectively set. 80 ° conduction width, and at the beginning of each output cycle, the switch elements are turned on to connect the outputs of the power supply units in series to supply power, and after a predetermined time of each output cycle, the switch elements The constant power output DC power supply control method is characterized in that the power is supplied by connecting the outputs of the power supply devices in parallel by turning off the power.

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